Compass



R. L. DODD Sept. 5, 1933.

COMPASS Filed May 16, 1951 2 Sheets-Sheet 1 Rufus 13.2045 ,igwz

ATTORNEY.

Sept. 5, 1933.

R. L. DODD COMPASS 2 Sheets-Sheet 2 Filed May 16, 1931 zzww 32 2 2/51. @mz

ATTORNEY.

Patented Sept. 5, 1 933 umrso STATES r-A'reur oFFicE A 2 Claims.

My invention relates to improvements in a compass.

The object of my invention is to provide a compass having means to approximately position the center point and pencil vertically, it being understood that each leg of the instrument may be equipped with a point or a pen may be substituted for a pencil.

A further object of my invention is to provide a compass having an automatic means to position the center point on one leg in parallelism with a pen or pencil point on the other leg as the legs of the instrument are rocked to and from each other at the free ends thereof.

A still further object of my invention is to provide a compass having a screw to expand and contract the free ends of the leg portions.

A still further object of my invention is to provide a divided nut to threadedly engage on the screw and means to detach the same therefrom for quick movement to set the compass near the desired radii and then adjust accurately by engagement of the nut.

These and other objects will hereinafter be more fully explained, reference being had to the accompanying drawings forming a part or" this specification, and in which like characters will apply to like parts in the different views.

Referring to the drawings:

Fig. 1 is a side view of the compass expanded.

Fig. 2 is a side view of the compass closed.

Fig. 3 is a transverse View of Fig. 2, one leg partly removed.

Fig. 4 is an enlarged top View of the compass.

Fig. 5 is an enlarged view of the pencil point retainer and a fragmentary portion of its respective leg.

Fig. 6 is a transverse or side view of Fig. 5, the rocking beam therefor being removed.

Fig. 7 is an enlarged view of a fragmentary portion of the other leg and center point pivoted thereto, and a portion of the rocking beam for the point.

Fig. 8 is an enlarged rear side View of the nut housing and link and fragmentary portion of each arm pivotally engaging with the same.

Fig. 9 is a plan View of Fig. 8, parts removed for convenience of illustration.

Fig. 10 is an enlarged vertical section thru the housing of the link and having a fragmentary portion of the screw shown in elevation, and one side of the nut being removed.

My compass herein disclosed consists of a threaded shaft 1 functioning as a screw to open and close the leg members hereinafter described,

the said screw being trunnioned in a cross head 2 and being shouldered to avoid longitudinal movement in the head. The shoulders are formed by a knurled knob 3 threadedly engaging on the outer end of the screw as shown by the co dotted lines in Fig. 1, while on the opposite side or" the head is a flange 4 integral with the shaft of the screw and the arrangement being such that the screw will turn in the head with a smooth running fit.

Pivoted to each end of the cross head is a leg 5 adapted to rock to and from the axis of the screw. Pivotally arranged on the outer end of one of the legs is a center point element 6 and on the end of the other leg is pivotally arranged a pencil gripping el ment consisting of a tubular element 7, the hollow of which is adapted to receive a pointed lead 8 slidable therein longitudinally and projecting as a marking element, the lower end of the tube is conical as at A and is split diametrically as shown at B, there being four of such splits, by which means the portion between the splits is adapted to move radially as gripping means for the lead when forced together by a collar 9 having a conical bore to conform to the conical portion of the tube and adapted to slide longitudinally thereon as releasing and grip- I ping means for the split portion. The collar has a tongue 10 integral therewith and extends substantially in parallelism with the axis of the 001- 35 lar. Positioned in the tongue is an elongated slot 11 to slidably engage on a stud 12 rigidly attached to sleeve '7, the said stud being threaded to receive a nut 13 threadedly engaging therewith as tensioning means for the tongue of the collar against retraction when thecollar is forced upward to contract the conical split portion binding the lead firmly therein.

Upwardly extending and attached to one side of the tube is an arcuate member 14. and a similar member 14' integral with the center point 6. To the outer end of each is pivotally attached a beam 15, the other end of which pivotally engages with an arm 16. The said arm pivotally 00 connects the said leg with its respective end of a link 17 that is conveyed along the said screw by a divided nut 18, the said nut being positioned in a housing C integral with the link, by which means the leg members are moved to and from the longitudinal axis of the screw as the said screw is turned, and at all times during the movement thereof the center point and mark retaining element are retained in approximate Parallelism thru the action of the movements 110.

of their respective arm and beam elements as the legs are moved to and from each other.

To cause a quick movement of the leg members, I have arranged a nut element in two parts and rockable to and from each other by a wing 19 laterally extending from each, and each wing engaging in a slot 20. The inside wall of each as at D being the fulcrum point to separate the nut. On the opposite side of each half of the nut is an outwardly extending ear 21 that engages in a slot 22 on the other 01" the housing portion. Each of the ears is apertured to engage on a pin 23 positioned in the slot as shown in Figs. 8, 9 and 10.

As a means to tension the ears toward each other, which is the closin means for each half of the nut to engage in mesh with the screw, a spring 24 is wound on the pin at each end thereof to engage between the outside of each ear and an end wall of the slot 22.

It is now clearly shown when the wings are pressed toward each other, the springs will com-- press for disengagement of the members of the nut, the link 17 is free to be moved longitudinally of the screw for adjusting the span of the leg members approximately as required, then by releasing the tension on the wings, the nut will engage with the screw for accurate adjustment, after which the instrument is ready to perform its duty and may be turned by the cross head or the knob.

Such modifications may be employed as lie within the scope of the appended claims, and having fully described invention what I claim as new and desire to secure by Letters Patent 1. In a compass, a pair of leg members and a cross head to which one end of each of said members is pivoted, a center point element carried by the free end of one leg and a pencil and pen supporting element pivotally carried on the free end of the other leg, a screw trunnioned in and carried by the cross head for turning only, a divided nut to threadedly engage on the screw and means to support the nut, arms connecting opposite sides of the said means to the leg members respectively, whereby the leg members may be moved to and from each other as the screw is turned, a beam pivotally connecting an intermediate portion or' each arm to the upper free ends of the center point and said pencil and pen supporting element respectively, whereby the center point and pencil and pen element are retained in parallelism as the leg elements are moved to and from each other.

2. In a compass, a cross head, a screw trunnioned in the center of the cross head and being shouldered to prevent longitudinal movement as the screw is turned, a leg element pivoted to each end of the cross head, a center point and pencil supporting element pivotally carried on the other end of the legs respectively, a link having a housing, and an arm pivotally connected to each side of the link, the other ends of the arms pivotally connected with mid points of the legs respectively, and a beam connecting each arm with the center point and pencil supporting element respectively to maintain the latter elements in parallelism as the free ends of the legs are moved to and from each other, a divided nut carried in the housing of the link, means to move the parts thereof to and from engagement with the screw for the purpose specified.

' RUFUS L. DODD. 

